Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-5181

incorrect binary search in remove_status_vars()

        Details

        • Type: Bug
        • Status: Closed
        • Priority: Critical
        • Resolution: Fixed
        • Affects Version/s: 10.0.4, 5.5.33a
        • Fix Version/s: 5.5.34, 10.0.6
        • Component/s: None
        • Labels:

          Description

          On INSTALL SONAME 'ha_tokudb.so' when TokuDB cannot be installed (for example, because transparent hugepages are enabled), MariaDB hangs.

          The reason is the remove_status_vars() function that has incorrectly implemented binary search to remove plugin variables from the all-variables list. The code

                for (; b-a > 0; c= (a+b)/2)
      {
        res= show_var_cmp(list, all+c);
        if (res < 0)
          b= c;
        else if (res > 0)
          a= c;
        else
          break;
      }

          in my test, a=129, b=130. So, c=129, in comparison I get res > 0, and the loop continues till infinity.

            Gliffy Diagrams

              Attachments

                Activity

                Ascending order - Click to sort in descending order
                Hide
                Permalink
                pomyk Patryk Pomykalski added a comment - - edited

                I came up with something like this:

                — sql/sql_show.cc 2013-07-16 17:09:54 +0000
                +++ sql/sql_show.cc 2013-11-05 21:59:41 +0000
                @@ -2550,17 +2550,18 @@

                for (; list->name; list++)
                {

                • int res= 0, a= 0, b= all_status_vars.elements, c= (a+b)/2;
                • for (; b-a > 0; c= (a+b)/2)
                  + int res= 0, a= 0, b= all_status_vars.elements, c;
                  + do { + c= (a+b)/2; res= show_var_cmp(list, all+c); if (res < 0) - b= c; + b= c - 1; else if (res > 0) - a= c; + a= c + 1; else break; - }

                  + } while (b >= a && a < all_status_vars.elements);
                  if (res == 0)
                  all[c].type= SHOW_UNDEF;
                  }

                Show
                pomyk Patryk Pomykalski added a comment - - edited I came up with something like this: — sql/sql_show.cc 2013-07-16 17:09:54 +0000 +++ sql/sql_show.cc 2013-11-05 21:59:41 +0000 @@ -2550,17 +2550,18 @@ for (; list->name; list++) { int res= 0, a= 0, b= all_status_vars.elements, c= (a+b)/2; for (; b-a > 0; c= (a+b)/2) + int res= 0, a= 0, b= all_status_vars.elements, c; + do { + c= (a+b)/2; res= show_var_cmp(list, all+c); if (res < 0) - b= c; + b= c - 1; else if (res > 0) - a= c; + a= c + 1; else break; - } + } while (b >= a && a < all_status_vars.elements); if (res == 0) all [c] .type= SHOW_UNDEF; }
                Hide
                Permalink
                bar Alexander Barkov added a comment -

                Pushed into 5.1, 5.2, 5.3, 5.5, 10.0-base.

                Show
                bar Alexander Barkov added a comment - Pushed into 5.1, 5.2, 5.3, 5.5, 10.0-base.

                  People

                  • Assignee:
                    bar Alexander Barkov
                    Reporter:
                    serg Sergei Golubchik
                  • Votes:
                    1 Vote for this issue
                    Watchers:
                    5 Start watching this issue

                    Dates

                    • Created:
                      Updated:
                      Resolved: